In general, ink jet printing machines or printers include at least one printhead that ejects drops or jets of liquid ink onto a recording or image forming media. A phase change ink jet printer employs phase change inks that are solid at ambient temperature, but transition to a liquid phase at an elevated temperature. The molten ink can then be ejected onto a printing media by a printhead directly onto an image receiving substrate, or indirectly onto an intermediate imaging member before the image is transferred to an image receiving substrate. Once the ejected ink is on the image receiving substrate, the ink droplets quickly solidify to form an image.
In various modes of operation, ink may be purged from the printheads to ensure proper operation of the printhead. When a solid ink printer is initially turned on, the solid ink is melted or remelted and purged through the printhead to clear air bubbles and/or contaminants from the printhead. The word “printer” as used herein encompasses any apparatus, such as digital copier, bookmaking machine, facsimile machine, multi-function machine, etc. that performs a print outputting function for any purpose. When ink is purged through the printhead, the ink flows down and off the face of the printhead typically to a waste ink tray or container positioned below the printhead where the waste ink is allowed to cool and re-solidify. The waste ink collection container is typically positioned in a location conveniently accessible so that the container may be removed and the waste ink discarded.
As an alternative to removing and discarding the waste phase change ink, some previously known systems have been configured to recycle the waste ink by directing it back to the melt reservoir that supplies the printhead with the melted phase change ink for jetting onto the image receiving substrate. Such systems typically use both positive and negative air pressure for pressurizing the reservoirs to force ink through the system in the desired direction.